bugtraq - Re: SSH host key fingerprint

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Message-ID: <20140901151627.GA3086@satori.lan>
Date: Mon, 1 Sep 2014 11:16:27 -0400
From: Chris Nehren <cnehren+bugtraq@...ox.com>
To: bugtraq@...urityfocus.com
Subject: Re: SSH host key fingerprint - through HTTPS

On Mon, Sep 01, 2014 at 12:41:17 +0800, John Leo wrote:
> This tool displays SSH host key fingerprint - through HTTPS.
> 
> SSH is about security; host key matters a lot here; and you can know
> for sure by using this tool. It means you know precisely how to answer
> this question:
> The authenticity of host 'blah.blah.blah (10.10.10.10)' can't be established.
> RSA key fingerprint is a4:d9:a4:d9:a4:d9a4:d9:a4:d9a4:d9a4:d9a4:d9a4:d9a4:d9.
> Are you sure you want to continue connecting (yes/no)?
> 
> https://checkssh.com/

Err, let me be sure I understand this tool properly.  You have a
web service--for which you do not provide the source code--that
provides the same information that an ssh client provides.  Not
providing the source code means that everything from malicious
manipulation to bugs are possible and the general public has no
means of verification that such do not exist.  Beyond that, as
said, it provides the same information that the ssh client does,
out of band, meaning that it's less convenient and thus less
likely to be used.

How, then, is this useful?  Sure, I can see the value in having
another point of presence to validate the ssh key of a
server--but ideally, if one cares about the key of a server
(which key, by the way?  The RSA key?  Or maybe the ECDSA?  Why
not DSA?), one should contact the system administrator over a
secure channel *before* connecting and establish the keys over
that channel.  Lacking source code and control over the server,
this service is just as vulnerable to all the attacks that I
assume your tool is attempting to mitigate.

It's Monday and I haven't had my tea yet, so maybe I'm missing
something.  What is it?

-- 
Chris Nehren

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